Integrated circuit sequencer

ABSTRACT

Electrophotographic copying apparatus is disclosed having an elongated electrosensitive web defining a plurality of selectable image areas and movable along an endless path relative to a plurality of actuable work stations disposed along the path. Each work station is operative when actuated to perform a work operation on a selected image area of the web. The apparatus includes an electronic sequencer for sequentially actuating particular ones of the work stations to cause them to perform work operations on the web in timed relation to movement of selected image areas along the path respectively. The sequencer includes a shift register having a plurality of states, the state at any particular time being a function of the position of the web along the path and the number of copies to be made. The sequencer further includes means for producing a first signal having a frequency proportional to the rate of movement of the web along the path, a counter responsive to the first signal and having a plurality of states, the state at any particular time manifesting the total cumulative number of first signals, and decoding networks responsive to particular states of the shift register and particular states of the counter for sequentially actuating and de-actuating the actuable work stations in timed relation to movement of the web past predetermined positions along the endless path to effect sequential operation of such work stations with respect to selected image areas.

United States Patent 1191 Lloyd 1451 May 8, 1973 [54] INTEGRATED CIRCUITSEQUENCER [75] Inventor: Gareth Aeron Lloyd, Rochester,

UNITED STATES PATENTS 6/1969 Hirsch ..328/37 X 7/1970 Gardner et al...355/3 Primary Examiner-Robert P. Greiner Att0rneyW. H. J. Kline et a1.

[57] ABSTRACT Electrophotographic copying apparatus is disclosed havingan elongated electrosensitive web defining a plurality of selectableimage areas and movable along an endless path relative to a plurality ofactuable work stations disposed along the path. Each work station isoperative when actuated to perform a work operation on a selected imagearea of the web. The apparatus includes an electronic sequencer forsequentially actuating particular ones of the work stations to causethem to perform work operations on the web in timed relation to movementof selected image areas along the path respectively. The sequencerincludes a shift register having a plurality of states, the state at anyparticular time being a function of the position of the web along thepath and the number of copies to be made. The sequencer further includesmeans for producing a first signal having a frequency proportional tothe rate of movement of the web along the path, a counter responsive tothe first signal and having a plurality of states, the state at anyparticular time manifesting the total cumulative number of firstsignals, and decoding networks responsive to particular states of theshift register and particular states of the counter for sequentiallyactuating and de-actuating the actuable work stations in timed relationto movement of the web past predetermined positions along the endlesspath to effect sequential operation of such work stations with respectto selected image areas.

3 Claims, 2 Drawing Figures .EATENTEUHAY' 81m sum 1 [1F 2 INTEGRATEDCIRCUIT SEQUENCER CROSS REFERENCE TO RELATED APPLICATIONS Reference ismade to commonly assigned U. S. Pat. application Ser. No. 19,644entitled, MAGNETI- CALLY CONTROLLED PROGRAMMER and commonly assigned U.S. Patent Application Ser. No. 19,999 entitled, MACHINE PROGRAMMER filedMar. 16, 1970, the disclosures of which are incorporated in theirentirety herein.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to apparatus for controlling the operational work stations inapparatus such as electrophotographic copying apparatus.

2. Description of the Prior Art In a common form of electrophotographiccopying apparatus, an electrical image of an information medium such asa document is formed on an electrophotosensitive medium in response toimage wise actinic radiation from the medium. The elec trophotosensitivemedium includes a photoconductive layer with a conductive backing, andis transported along an endless path relative to a plurality of workstations, each of which is operative when actuated to perform a workoperation on the electrophotosensitive medium. Such stations include acharging station at which a uniform charge is placed on thephotoconductive layer, an exposure station at which the chargedphotoconductive layer is image-wise exposed to actinic radiation fromthe medium to create an electrostatic image of the medium in thephotoconductive layer, a developing station at which the electrostaticimage is contacted with finely divided charged toner particles adheringto the photoconductive layer in a configuration defined by theelectrostatic image, a transfer station at which such toner particlesare transferred in the image configuration to a receiving surface, and acleaning station at which residual toner is removed from thephotoconductive layer so that it can be reused.

In applications in which the electrophotosensitive medium is continuallyreused, it can be constructed in a form of a drum, a plate or an endlessweb. The endless web configuration has certain advantages anddisadvantages over drums and plates. Among the advantages is the factthat such a web can be disposed in flat con figuration at one locationin the apparatus to facilitate some operations such as, e.g., exposureand in curved configurations at other locations to facilitate otheroperations such as separation of a transfer sheet therefrom. Among thedisadvantages is the increased complexity of the system resulting fromthe need to sequentially actuate work stations in timed relation to webmovement and control the number of copies to be made.

SUMMARY OF THE INVENTION It is an object of this invention to providefor use in an electrophotographic copying apparatus improved apparatusfor controlling the sequential actuation of work stations andcoordinating such actuations with the number of copies to be made.

In accordance with a preferred embodiment of this invention, there isdisclosed an elongated electrophotosensitive web defining a plurality ofselectable image areas and movable along an endless path relative to aplurality of actuable work stations wherein each work station whenactuated performs an operation in conjunction with the web. Theapparatus includes sequencing means for sequentially actuating andde-actuating the work stations in timed relation to movement of the webpast predetermined positions along the endless path to effect sequentialoperations of such work stations with respect to a selected image areaduring movement of said area around said endless path. The sequencingmeans includes means for sequentially providing a first signal withfirst signal being representative of copy of an original to be made,means responsive to such first signal and having a plurality of states,

the state at any particular time being representative of the totalcumulative number of first signals. The sequencing means furtherincludes means for producing second signals having a frequency which isa function of the rate of speed of the web along the path, counter meansresponsive to the second signals and having a plurality of states, thestate at any particular time being representative of the totalcumulative number of second signals produced in response to movement ofa selected image area relative to a predetermined position along thepath and means responsive to particular states of the shift register andparticular states of the counter means to effect sequential operation ofthe actuable stations with respect to selected image areas duringmovement of the web along the endless path.

l BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showingthe general arrangement of a web type electrophotographic copyingapparatus in accordance with the invention; and

FIG. 2 is a block diagram of the sequencer device shown in FIG. 1 forcontrolling the actuation of various work stations in theelectrophotographic apparatus shown in FIG. 1.

The symbols for the logic components shown in the drawings are inaccordance with American Standard Graphical Symbols for Logical Diagrams(ASA) & 32.14-1962.

DESCRIPTION OF THE PREFERRED EMBODIMENT Turning first to FIG. 1, thereis shown an electrophotographic apparatus E that includes anelectrophotosensitive member in the form of a web 2 which includes aphotoconductive surface on a photoconductive backing and which defines aplurality of selectable image areas; a plurality of actuable workstations; and a sequencer S disclosed more fully in connection with FIG.2. The web 2 has a leading end attached to a tow bar 4 by studs 16 andis movable along an endless path past rollers 6, 8, 10, 12 and 14respectively as disclosed more fully in commonly assigned U. S.copending application Ser. No. 843,695 entitled, WEB HANDLING APPARATUSAND CARTRIDGE AND WEB USA- BLE THEREWITI-I to Thaddeus Swanke, filedJune 9, 1969. Roller 8 is a drive roller for the web 2 and is driventhrough a drive train which includes a main drive motor 18, an electricclutch 20, a brake 22 and a clutch 24. The clutch 24 has two selectabledriving positions. When it is in the first position, the clutch 24 iseffective to serve as a driving connection between the main drive motor18 andphotoconductive belt 2, and when it is moved to the secondposition, it serves as a driving connection between a thread-unthreadmotor 21.

In operation, the photoconductive belt 2 is moved along an endless pathpast a plurality of actuable work stations, e.g., charging station 26,imaging station, developing station 40 and and transfer station 42 alllocated along the path.

The charging station 26 includes a power supply 26a and a corona wirestructure 26b which is operative when actuated by a signal transmittedby conductor 260 from the sequencer S to provide a generally uniformelectrostatic charge on a selected image area of the web 2. Thereafter,such charged image area is exposed to a pattern of actinic radiation atan actuable exposure station 28 where the image of an original 30 isilluminated by a plurality of high intensity light sources 32 when theyare activated by a signal transmitted by conductor 28a from thesequencer S and light from the document is projected upon the opening ofa shutter 38. The electrostatic charge in the exposed areas is thendissipated leaving an electrostatic latent image. This latent image isdeveloped by toner particles applied at a continuously operatingdeveloping station 40. The toner particles may have a charge opposite inpolarity to that of the charge from the electrostatic image and areattracted theretoto form a toner image. The toner image is then advancedthrough movement of the web along its endless path to the vicinity of anactuable image transfer station 42 which in response to a signaltransmitted by lead 42a from the synchronizer S is actuated insynchronism with the arrival of a receiver sheet feed from a papersupply 44 which is fed by means of a sheet feeder 43. The sheet feederin turn is actuatable in response to a signal transmitted by lead 43afrom the synchronizer S and includes a vacuum finger 46 which deliversthe receiver sheet to a pair of oppositely rotating feeder rollers 48and 511 so that the receiver sheet is brought into face-to-face contactwith the toner image at the transfer station 42 whereupon the tonerimage is transferred from the photosensitive web to a receiver .sheet.The receiver sheet is then transported to a receiver hopper or to asheet sorter shown generally at 52. Various forms of suitable sheetfeeders are known in the art; however, the sheet feeder disclosed incommonly assigned copending U. S. Pat. application Ser. No. 23,705entitled, PAPER FEED AND EXPOSURE SYNCHRONIZER to Jorgen Reesen filedMar. 30, 1970 is especially suitable for use with the apparatus E. Theremaining station, a cleaning station 54, may include an erase lamp,actuable in response to a signal conducted by lead 54a from thesequencer S. It will be understood to those skilled in the art that aplurality of (in this instance, five) electrostatic and toner images maybe placed sequentially on successive portions of the web as it movesalong the endless path so that the above discussed work operationsperformed at the work stations occurs in proper timed sequence ondifferent portions of the web which correspond to selected image areas.

Turning now to FIG. 2, the sequencer S includes a logic circuit 49 whichreceives signals from a shaft encoder depicted schematically to includea cam 49c mounted on the main drive shaft of the roller 8 and which isadapted to open and close a switch 49b as the shaft rotates. Logiccircuit 49 is adapted to produce a signal conducted by a lead 49a eachtime one of the selectable image areas advances to a position adjacentthe charging station 26 along the path. Thus, logic 49 is adapted toprovide five discrete signals for each complete cycle of operation ofthe web, viz., each time a particular point on the web completelytraverses the entire endless path. The sequencer S further includes ashift register 50 having five flip-flop memory stages (Sim-e). The shiftregister 50 is responsive to signals conducted by the lead 49a producedby the logic 49. The contents of flip-flop 50e are lost each time ashift command signal is provided in lead 49a. As will be apparent tothose skilled in the art, the flip-flops 50a-e are placed in a reset orzero state just prior to commencing operation. A logic circuit 56 willbe understood to include a counter preset with the number of copies tobe made and is adapted to receive a count signa in lead 56a from thesequencer S. Reference is made to commonly assigned copendingapplication entitled, CONTROL APPARATUS FOR ELECTRPHOTOGRAPHICAPPARATUS, filed Oct. 21-, 1971 in the names of Lionel Hickey and FrankGuyette which discloses logic apparatus which provides the functions ofcircuit 56. As shown in FIG. 1 of such disclosure the circuit 56 mayinclude a counter 14 responsive to signals from a photocell 132, withthe total cumulative number of such signals being representative of thenumber of copies which have been made.

Returning to FIG. 2, when the web is at rest, a clear signal isgenerated which resets all of the stages of the shift register 50 to areset, condition. When the motor 18 (FIG. 1) is energized and the web 2begins to rotate, the control logic 56 is rendered effective and willproduce a high level input signal to the shift register 50 for so longas the number of control signals is less than the number of copies to bemade which has been entered into a preset counter. Thus, when the logic49 produces a signal for a predetermined time duration, lead 49g isenergized and causes a binary bit to be entered into the first stage 50aof the shift register 50. In a similar fashion the shift registercontinues to receive and enter bits upon receiving signals from logic 56and lead 49a. In this manner, the state of the shift register 50 at anyparticular time (hereinafter called present state of the shift register50) is a function of (a) the position of the web along the path, and (b)the number of copies to be made.

In FIG. 2, there is also provided a logic circuit block 60 coupled tothe logic block 49. The logic 60 is adapted to provide a clock or signalin lead 60a which has a frequency proportional to the rate of speed ofthe web to a counter 70. In one exemplary embodiment, the clock has afrequency of 250 pulses per second, when one complete revolution of theweb is accomplished in four-and-one-half seconds. If the web speedshould change, the frequency of the clock will change in directproportion thereto. The clock is continuously operated at thepredetermined frequency and provides its output directly to a counter 70having eight flipflops (not shown). Counter circuits in accordance withthe invention are commercially available and may take various forms suchas for example, Model MC93161 or MC83l6lp manufactured by the MotorolaSemiconductive Products, Inc., as disclosed in Motorolas Handbook TTLINTEGRATED CIRCUITS DATA BOOK 1970). The counter 70 has a plurality ofstates, the state of the counter 70 at any particular time (hereinafterthe present state of the counter 70) is representative of the totalcumulative number of pulses of the clock which are received. However, itshould be noted that each time a signal is produced in lead 490 whichcorresponds in time to when a selected image area moves past apredetermined position along the path, the counter circuitry 70 will bereset to a state which represents a zero total count. Eight leads(81-88), couple the l side of each flip-flop stage in the counter 70 todecoder 80. Decoders may take various forms well known in the art andwhich are adapted to provide outputs over selective lead linescorresponding to particular total cumulative counts held within thecounter 70. An example of such a decoder which may be directly used withthe counter 70 is Model MC831 1p manufactured by Motorola and disclosedin the aforementioned Motorola data handbook. A second decoder 90 iscoupled to the shift register 80 and decodes various present states ofthe shift register and is adapted to provide sequential outputs whichdepend upon the particular ones of the present states of the counter 70which are decoded by the decoder 80 and particular ones of the presentstates of the shift register 50. The decoders are readily adjustable andso may be made to be responsive to different particular states of thecounter 70 in order to compensate for operational characteristic of thevarious devices. In this way, sequential output control signals may beprovided which correspond directly with those signals shown in theaforementioned patent applications disclosed in this'section entitled,CROSS REFERENCE TO RE- LATED APPLICATIONS. Each of the sequential outputsignals of the decoder 90 are adapted to sequentially actuate particularones of the work stations. The following simplified truth table showsthe relationship between the operative counts held by the counter 70,the present state of the shift register 50 and the output signals of thesequencer S for the count line 28a, in the aforementioned example wherethe input signal conducted by lead 60a is at a frequency of 250 pulsesper second.

TRUTH TABLE 81 0101 0 101 32 0011 1 011 as 0000 0 111 $4 0000 0 111 as0000 1 111 as 0000 1 111 87 0000 o 111 as 0000 1 111 50a 0000 1 111 28a0000 1 000 NOTE: Output 280 is logic 0 for all combinations not shownexplicitly in the table.

The present invention has been described in considerable detail withparticular reference to a preferred embodiment thereof, but it will beunderstood that variations and modifications can be effected within thespirit and scope of the invention.

I claim:

1. In electrophotographic apparatus having an elongatedelectrophotosensitive web adapted to have an electrostatic image formedthereon and means for transferring information contained in such imageto a receiver sheet in image transfer relation with the web, thecombination comprising:

a. a plurality of actuable work stations including an actuable chargingstation operative when actuated for charging a selected portion of theweb, an actuable exposure station operative when actuated for forming anelectrostatic image on a charged portion of the web, and an actuablesheet feeder operative when actuated for feeding the receiver sheet intoimage transfer relation with such electrostatic image formed on the web;

b. means for moving the web along an endless path past relative to saidplurality of actuable work stations; and

c. means for sequentially actuating and de-actuating said charging,exposure and transfer stations in timed relation to movement of the webpast predetermined positions along said path comprising:

i. a shift register coupled to said electrophotosensitive moving meansand having a plurality of states, the present state of which is afunction of the position of the web along the endless path;

ii. means coupled to said moving means and effective to produce clocksignals at a frequency which is a function of the rate of speed ofmovement of the web along the path;

iii. counter means independent of said shift register and responsive tosaid clock signals and having a plurality of states, the present stateof which is representative of the total cumulative number of said clocksignals; and

iv. decoder means coupled to said counter means and said shift registerand responsive to particular ones of the present states of said shiftregister and particular ones of the present states of said counter meansto effect sequential operation of said charging, exposure and transferstations with respect to said selected portion during movement of theweb along the endless path respectively.

2. In electrophotographic apparatus having an elongatedelectrophotosensitive web adapted to have an electrostatic image formedthereon and means for transferring information contained in such imageto a receiver sheet in image transfer relation with the web, thecombination comprising:

a. a plurality of actuable work stations including an actuable chargingstation operative when actuated for charging a selected portion of thephotosensitive web, an actuable exposure station operative when actuatedfor forming an electrostatic image on a charged portion of the web, andan actuable sheet feeder operative when actuated for feeding thereceiver sheet into image transfer relation with such electrostaticimage formed on the web;

. means for moving electrophotosensitive web along an endless path pastrelative to said plurality of actuable work stations; and

means coupled to said web moving means for producing a first signal eachtime a selected image area moves past a predetermined position along theweb;

. a shift register responsive to said first signals and having aplurality of states, the present state of which is solely a function ofthe total cumulative number of said first signals;

iii. means coupled to said web moving means and effective toproduceclock signals at a frequency which is a function of the rate of speed ofthe web along the path;

iv. counter means independent of said shift register responsive to saidclock signals and having a plurality of states, the present state ofwhich is representative of the total cumulativenumber of said clocksignals; and

. at least one decoder coupled to said counter and said shift registerand simultaneously responsive to particular ones of the present statesof said shift register and particular ones of the present states of saidcounter means to effect sequential operation of said charging, exposureand transfer stations with respect to said selected portion duringmovement of the web along the endless path respectively.

3. The invention as set forth in claim 2 wherein said decoder means isadjustable to be responsive to different ones of particular states ofsaid counter means.

1. In electrophotographic apparatus having an elongatedelectrophotosensitive web adapted to have an electrostatic image formedthereon and means for transferring information contained in such imageto a receiver sheet in image transfer relation with the web, thecombination comprising: a. a plurality of actuable work stationsincluding an actuable charging station operative when actuated forcharging a selected portion of the web, an actuable exposure stationoperative when actuated for forming an electrostatic image on a chargedportion of the web, and an actuable sheet feeder operative when actuatedfor feeding the receiver sheet into image transfer relation with suchelectrostatic image formed on the web; b. means for moving the web alongan endless path past relative to said plurality of actuable workstations; and c. means for sequentially actuating and de-actuating saidcharging, exposure and transfer stations in timed relation to movementof the web past predetermined positions along said path comprising: i. ashift register coupled to said electrophotosensitive moving means andhaving a plurality of states, the present state of which is a functionof the position of the web along the endless path; ii. means coupled tosaid moving means and effective to produce clock signals at a frequencywhich is a function of the rate of speed of movement of the web alongthe path; iii. counter means independent of said shift register andresponsive to said clock signals and having A plurality of states, thepresent state of which is representative of the total cumulative numberof said clock signals; and iv. decoder means coupled to said countermeans and said shift register and responsive to particular ones of thepresent states of said shift register and particular ones of the presentstates of said counter means to effect sequential operation of saidcharging, exposure and transfer stations with respect to said selectedportion during movement of the web along the endless path respectively.2. In electrophotographic apparatus having an elongatedelectrophotosensitive web adapted to have an electrostatic image formedthereon and means for transferring information contained in such imageto a receiver sheet in image transfer relation with the web, thecombination comprising: a. a plurality of actuable work stationsincluding an actuable charging station operative when actuated forcharging a selected portion of the photosensitive web, an actuableexposure station operative when actuated for forming an electrostaticimage on a charged portion of the web, and an actuable sheet feederoperative when actuated for feeding the receiver sheet into imagetransfer relation with such electrostatic image formed on the web; b.means for moving electrophotosensitive web along an endless path pastrelative to said plurality of actuable work stations; and c. means forsequentially actuating and de-actuating said charging, exposure andtransfer stations in timed relation to movement of the web pastpredetermined positions along said path comprising: i. means coupled tosaid web moving means for producing a first signal each time a selectedimage area moves past a predetermined position along the web; ii. ashift register responsive to said first signals and having a pluralityof states, the present state of which is solely a function of the totalcumulative number of said first signals; iii. means coupled to said webmoving means and effective to produce clock signals at a frequency whichis a function of the rate of speed of the web along the path; iv.counter means independent of said shift register responsive to saidclock signals and having a plurality of states, the present state ofwhich is representative of the total cumulative number of said clocksignals; and v. at least one decoder coupled to said counter and saidshift register and simultaneously responsive to particular ones of thepresent states of said shift register and particular ones of the presentstates of said counter means to effect sequential operation of saidcharging, exposure and transfer stations with respect to said selectedportion during movement of the web along the endless path respectively.3. The invention as set forth in claim 2 wherein said decoder means isadjustable to be responsive to different ones of particular states ofsaid counter means.